<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <title>系统导航</title>
    <style>
        body {
            font-family: Arial, sans-serif;
            padding: 40px;
            background-color: #f5f5f5;
        }
        .container {
            max-width: 600px;
            margin: 50px auto;
            background: white;
            padding: 30px;
            border-radius: 8px;
            box-shadow: 0 2px 8px rgba(0,0,0,0.1);
        }
        h1 {
            text-align: center;
            color: #333;
            margin-bottom: 30px;
        }
        .nav-grid {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 20px;
            margin-top: 20px;
        }
        .card {
            background-color: #007bff;
            color: white;
            padding: 20px;
            border-radius: 5px;
            text-align: center;
            transition: transform 0.2s;
        }
        .card:hover {
            transform: translateY(-5px);
            background-color: #0056b3;
        }
        .card a {
            color: white;
            text-decoration: none;
            font-weight: bold;
        }
    </style>
</head>
<body>
<div class="container">
    <h1>数据管理系统</h1>

    <div class="nav-grid">
        <div class="card">
            <h2>用户登录</h2>
            <a href="login.html">进入用户登录</a>
        </div>

        <div class="card">
            <h2>管理员登录</h2>
            <a href="login.html">进入管理员登录</a>
        </div>

        <div class="card">
            <h2>用户注册</h2>
            <a href="register.html">立即注册</a>
        </div>

        <div class="card">
            <h2>系统文档</h2>
            <a href="/doc.html">查看API文档</a>
        </div>
    </div>
</div>
</body>
</html>
